This application claims the priority of Korean Patent Application No. 2003-65223, filed on Sep. 19, 2003, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to a magnetic recording head, and more particularly, to a magnetic recording head, which includes a plurality of shield layers formed on a writing pole to prevent magnetic fields generated inside and outside the magnetic recording head from concentrating on a return pole and to effectively write and erase information on an information recording media.
2. Description of the Related Art
Studies of a perpendicular magnetic recording method are actively performed all over the world to increase a recording density in a magnetic information recording field. In the perpendicular magnetic recording method, magnetization is oriented perpendicular to a disk surface to increase a recording density, unlike a general longitudinal magnetic recording method. The perpendicular magnetic recording method writes information using a writing pole.
FIG. 1 is a perspective view of a conventional magnetic read/write head in an apparatus for writing and reading a magnetic signal on a predetermined recording media, such as a hard disk drive (HDD). As shown in FIG. 1, a magnetic head 10 is installed on a slide 12 disposed on one end of a swing arm 11, and is moved to a desired position over a recording media by pivoting of the swing arm 11 to perform write and read operations.
FIG. 2 is an enlarged view of the magnetic head 20 shown in FIG. 1. As shown in FIG. 2, the magnetic head 20 includes a magneto-resistive head 21 for a read operation and a magnetic recording head for a write operation. The magneto-resistive head 21 detects and reads a magnetic signal recorded on the recording media. The magnetic recording head includes a writing pole 22 for forming leakage magnetic flux to the recording medium, a return pole 23, and a writing coil 24 acting as a current supply route, and records a magnetic signal of a desired content on the recording media.
In particular, the magnetic recording head determines the quality of a signal input to the recording media. If the signal input via the magnetic recording head is not clean, the magneto-resistive head cannot perform satisfactory reproduction although it has an excellent performance. The magnetic recording head is very sensitive to an external magnetic field. For example, a magnetic field from a voice coil motor (VCM) that drives the swing arm 11 is introduced to the magnetic recording head, an undesired external magnetic field concentrates on the magnetic recording head. This phenomenon is referred to as an antenna effect. The external magnetic field concentrating on the magnetic recording head causes wrong information to be written on the recording media or information on the recording media to be erased.
FIG. 3A illustrates the flow of a magnetic field when information is written on an information recording media, such as a HDD, using a magnetic recording head.
A conventional magnetic recording head 30 includes a return pole 32, a writing pole 33 spaced by a predetermined distance from the return pole 32, an induction writing coil 34 for forming a magnetic field across the writing pole 33, and a shield layer 35 formed on the writing pole 33. The writing pole 33 writes information on an information recording media 31 that is generally formed by depositing a writing layer on a soft magnetic layer. As shown in FIG. 3A, a magnetic field that moves from the writing pole 33 and passes through the return pole 32 and the shield layer 35 forms an oval shape. If a magnetic field passing through the return pole 32 in a magnetic recording head without the shield layer 35 becomes larger, the magnetic field causes a noise to the recording media. To prevent the noise, the shield layer 35 is formed on the writing pole 33 so that part of the magnetic field flowing toward the return pole 32 can be distributed to the shield layer 35, and thus, the strength of the magnetic field directed toward the return pole 32 can be reduced.
When magnetic writing is performed, magnetic flux from the writing pole 33 separately flows to the return pole 32 and the shield layer 35. Here, since the return pole 32 is not magnetically connected to the writing pole 33, the magnetic flux flowing toward the return pole 32 decreases relatively, and the magnetic flux flowing toward the shield layer 35 increases. If a large amount of magnetic flux flows to the shield layer 35, the large amount of magnetic flux causes a noise that obstructs writing, thereby reducing the effect of the shield layer 35.
FIG. 3B illustrates the flow of a magnetic field generated by an external magnetic field source, such as the swing arm or the VCM for driving the swing arm, other than the magnetic recording head 30. The magnetic flux concentrates on an end of the writing pole 33 due to structural characteristics of the writing pole 33 and a large amount of magnetic flux flows through the writing pole 33. The large amount of magnetic flux causes a noise when the information recording media 31 performs writing. The shield layer 35 is employed to reduce the influence of the external magnetic field.
However, the shield layer 35 formed on the writing pole 33 has a limitation in reducing the adverse effects of the magnetic fields generated inside and outside the magnetic recording head 30 as shown in FIG. 3A and FIG. 3B, respectively. That is, the shield layer 35 hardly reduces the influence of the external magnetic field on the writing pole 33, such that the external magnetic field affects and still obstructs the writing function of the writing pole 33. Although the external magnetic field generated outside the magnetic recording head 30 is small, the external magnetic field at the writing pole 33 becomes larger sharply due to a bottleneck.